Image enhancement of wide-field retinal optical coherence tomography angiography by super-resolution angiogram reconstruction generative adversarial network

Wide-field retinal optical coherence tomography angiography (OCTA) usually suffers from low image resolution in clinical practice because of insufficient lateral sampling. In this study, we develop a deep-learning-based method named super-resolution angiogram reconstruction generative adversarial network (SAR-GAN) to enhance the en face OCTA image quality. A sophisticated home-made spectral-domain OCTA system is employed to capture the data of retinal angiograms with different scanning protocols. High-resolution 3 x 3 mm2 OCTA images and low-resolution (LR) 6 x 6 mm2 OCTA images are utilised in training the network. We propose an improved loss function for SAR-GAN for the reconstruction of perceptually enhanced super-resolution images. The well-trained network is utilized to processing the LR OCTA images with a field of view (FOV) of 3 x 3 mm2, 6 x 6 mm(2) and as large as 9 x 9 mm2. The qualitative and quantitative comparisons show that SAR-GAN provides perceptually better visualization and significantly enhances the image quality in terms of noise in-tensity, contrast-to-noise ratio and vessel connectivity. Moreover, it demonstrates superior image enhancement for retinal OCTA with small or large FOVs, compared with other traditional and deep-learning based methods. The SAR-GAN has great potential to improve the clinical assessment by wide-field OCTA.

Automated summary

The study introduces a deep-learning-based approach named SAR-GAN to enhance the image quality of wide-field retinal OCTA. By utilizing high and low-resolution OCTA images in training, the network is capable of reconstructing improved super-resolution images with better visualization, noise intensity, contrast-to-noise ratio, and vessel connectivity. The SAR-GAN demonstrates superior image enhancement for both small and large FOVs compared to traditional and other deep-learning methods, showing great potential for clinical assessment improvement with wide-field OCTA.